Many different types of rheological agents are used in non-aqueous fluid systems such as paints, varnishes, enamels, waxes, epoxies, mastics and the like. These fluid systems often contain finely divided suspended materials, such as pigments and the like. Rheological agents are added to provide viscosity control, sag control, pigment suspension, and related benefits.
Various organo modified clays and other inorganic and organic compounds have been used in the past to produce these rheological effects. The organophilic clays, however, which have been used in prior compositions require the use of polar solvent activators and are usually added during manufacture. If the polar solvent activators are not used, the desired rheological properties, viscosity build, sag control and pigment setting control are not fully achieved, that is, only a portion of the clay's thickening ability is obtained. Dispersion of these organophilic clays are difficult in systems such as low viscosity paints. Proper activation at point of manufacture is also difficult.
U.S. Pat. No. 3,977,894 issued Aug. 31, 1976 to Robert W. White et al discloses a self-activating organoclay rheological additive for non-aqueous fluid systems which is a homogeneous mixture of an organically modified montmorillonite clay and two solid waxes, glyceryl tri-12-hydroxystearate and an amide wax. The amide wax has the formula R--NH--(CH.sub.2).sub.n --NH--HSA wherein n is from one to eighteen, HSA is the acyl radical of 12-hydroxystearic acid and R is HSA or hydrogen. This system requires the fluid system to be heated during the addition of the special self-activating clay. This heat requirement is difficult to obtain if the paint system, for example, is of low viscosity, and the shear effect during paint processing does not develop sufficient heat. Further this cannot be used for correcting the viscosity of let-down finished paints since the paint is always at approximately room temperature. U.S. Pat. No. 4,208,218 issued June 17, 1980 to Claude M. Finlayson discloses an organoclay rheological addition for non-aqueous fluid systems comprising a smectite-type clay and a benzyl dialkyl ammonium compound. The use of a benzyl compound as derived from coal tar origin is potentially hazardous for such paint applications as coating for food cans, food package coatings and similar uses.
It is an object of this invention to provide an additive for controlling the viscosity, sag and pigment suspension of a non-aqueous fluid system which does not require heating of the fluid system or shear dispersion. Another object of the invention is to provide a simplified product which does not require further treatment at the point of manufacture. Other objects and the advantages of the invention will appear from the following detailed description.